From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933146Ab2IFUwQ (ORCPT ); Thu, 6 Sep 2012 16:52:16 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:43258 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933119Ab2IFUwN (ORCPT ); Thu, 6 Sep 2012 16:52:13 -0400 Date: Thu, 6 Sep 2012 13:51:56 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, "Paul E. McKenney" Subject: Re: [PATCH tip/core/rcu 01/15] rcu: Add PROVE_RCU_DELAY to provoke difficult races Message-ID: <20120906205156.GZ2448@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20120830185607.GA32148@linux.vnet.ibm.com> <1346352988-32444-1-git-send-email-paulmck@linux.vnet.ibm.com> <1346942312.18408.26.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1346942312.18408.26.camel@twins> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12090620-5518-0000-0000-0000076F8DC1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 06, 2012 at 04:38:32PM +0200, Peter Zijlstra wrote: > On Thu, 2012-08-30 at 11:56 -0700, Paul E. McKenney wrote: > > +#ifdef CONFIG_PROVE_RCU_DELAY > > + udelay(10); /* Make preemption more probable. */ > cond_resched(); /* for extra fun? */ The additional fun could include "scheduling while atomic", so I will pass. ;-) (The problem is that __rcu_read_unlock() can be called with interrupts disabled, among other things.) Thanx, Paul > > +#endif /* #ifdef CONFIG_PROVE_RCU_DELAY */ > >